David B. Agus, MD notes in his book "A Short Guide to a Long Life" (page 158) that we "breathe in 2,000 gallons of air a day into an organ with the surface area of a tennis court."

That's your lungs. They fit in your chest but due to the complexity of the inner surface where the air you breathe meets your blood their working surface area is extensive.

So how much of that surface area do you use? If you are not breathing deeply, you do not use it all, certainly not to its capacity.

And what happens to unused organs in the body? If you do not use all of the lungs' capacity for exchange of oxygen and waste, what happens to the portions of your lungs you are not using fully? Do they remain fit and available for use, or do they harbor disease or become unusable over time?

Breathe more deeply once a day. Not in the sense of sitting and taking one or more deep breaths. Get your body moving. Let your body decide how deep to breathe. Keep moving until you know you are using a greater portion of your lungs with deeper breaths.

One reason rowing is such a useful exercise is that it uses a high percentage of the body at once (joints, muscle mass, etc.). That greater simultaneous demand more readily creates a greater demand on the lungs. It is an efficient way to breathe more deeply and, thus, to gain the benefits of your lung power.

Is it fair to say that hard working lungs are happy lungs? Maybe that is too simple, potentially misleading. But you get the point.